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United States Patent |
5,601,580
|
Goldberg
,   et al.
|
February 11, 1997
|
Venous valve cutter
Abstract
An improved valve cutter for in-situ incision of valve leaflets which
safely, efficiently, and consistently renders venous valves incompetent
while minimizing frictional forces on the endothelium of the vessel and
preventing inadvertent contact between cutting surfaces and the intima of
the vein wall. The valve cutter includes a plurality of proximally
directed prongs presenting sharp edges, where the prongs are separated by
slots similarly presenting sharp edges to pierce the valve leaflets so
that the cutting head is provided with a continuous cutting surface in
multiple planes running along the entire forward edge of the cutting head.
Fiber optics provided for viewing the valves as they are penetrated by the
sharp cutting edges.
Inventors:
|
Goldberg; Mark C. (Boston, MA);
Poloyko; Alexander (Morton Grove, IL)
|
Assignee:
|
Uresil Corporation (Skokie, IL)
|
Appl. No.:
|
313229 |
Filed:
|
January 9, 1995 |
PCT Filed:
|
April 9, 1993
|
PCT NO:
|
PCT/US93/03358
|
371 Date:
|
January 9, 1995
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102(e) Date:
|
January 9, 1995
|
PCT PUB.NO.:
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WO93/20764 |
PCT PUB. Date:
|
October 28, 1993 |
Current U.S. Class: |
606/159 |
Intern'l Class: |
A61B 017/32 |
Field of Search: |
606/159,167,170,179,194
604/22
|
References Cited
U.S. Patent Documents
3837345 | Sep., 1974 | Matar.
| |
4493321 | Jan., 1985 | Leather.
| |
5026383 | Jun., 1991 | Nobles | 606/159.
|
5047041 | Sep., 1991 | Samuels | 606/159.
|
Foreign Patent Documents |
3717926 | Dec., 1988 | DE | 606/159.
|
0537676 | Dec., 1976 | SU | 606/159.
|
Other References
American V. Mueller The Surgical Armamentarium p. 98 (1980).
|
Primary Examiner: Buiz; Michael Powell
Assistant Examiner: Rasche; Patrick W.
Attorney, Agent or Firm: Laff, Whitesel, Conte & Saret, Ltd.
Parent Case Text
This is a 371 CPU/US93/03358 filed on Apr. 4, 1993 which is a
continuation-in-part of U.S. patent application Ser. No. 07/865,850 filed
Apr. 4, 1992 now U.S. Pat. No. 5,304,189.
Claims
What we claim is:
1. A method of in-situ removal of venous valve leaflets from a saphenous
vein having a proximal end and a distal end and a lumen tapering from its
distal end to its proximal end comprising:
a) introducing at the proximal end of the vein a valve cutter assembly with
a blunt-tipped head and an irrigation channel at its distal tip;
b) introducing fluid through the distal tip of the blunt-tipped head to
dilate the vein and, with the vein distended, advancing the valve cutter
assembly distally;
c) removing the blunt-tipped head when the assembly reaches the
sapheno-femoral junction or an adequate distal tributary of the saphenous
vein and replacing it with an appropriately sized valve cutter head also
having an irrigation channel at its distal tip and clamping the saphenous
vein at its open fossa ovalis or distal to the distal saphenous valve;
d) positioning the valve cutter head at the distal end of the vein,
injecting fluid through the channel in the cutter head thereby closing the
valve;
e) pulling back on the valve cutter assembly to engage and cut the most
distal valve and then maintaining hydrostatic pressure while the valve
cutter assembly is pulled down to engage and cut each sequential valve
until all valves have been rendered incompetent; and
f) repeating steps d) and e) with a plurality of appropriately sized valve
cutter heads to match the heads to the vein's tapering lumen.
2. An improved venous valve cutter comprising:
a cutter head having a forward circular cutting edge and means for
advancing said cutter head through a vein to render valve leaflets
incompetent,
said circular cutting edge having a plurality of proximally directed prongs
presenting sharp leading edges,
said prongs having flat leading edges and being separated by slots
similarly presenting sharp cutting edges; and
fiber optic means directed distally and positioned proximally to the
circular cutting edge for viewing the cutting of the venous valve leaflets
as the cutting edge of the valve cutter advances through the vessel and
assessing the cut.
3. An improved venous valve cutter comprising:
a cutter head having a forward circular cutting edge and means for
advancing said cutter head through a vein to render valve leaflets
incompetent,
said circular cutting edge having a plurality of proximally directed prongs
presenting sharp leading edges,
said prongs having flat leading edges and being separated by slots
similarly presenting sharp cutting edges;
a leader having a diameter generally equal to that of said cutter head and
a stem connecting said cutter head and said leader; and
fiber optic means mounted in the leader proximal to the circular cutting
edge for viewing the cutting of the venous valve leaflets by the cutting
edge as the valve cutter advances through the vein and assessing the cut.
4. An improved venous valve cutter comprising:
a cutter head having a forward circular cutting edge and means for
advancing said cutter head through a vein to render valve leaflets
incompetent,
said circular cutting edge having a plurality of proximally directed prongs
presenting sharp leading edges,
said prongs having flat leading edges and being separated by slots
similarly presenting sharp cutting edges; and
fiber optic means mounted in the leader proximal to the circular cutting
edge for viewing the cutting of the venous valve leaflets by the cutting
edge as the valve cutter advances through the vein and assessing the cut.
5. A method of in-situ removal of venous valve leaflets from a vein having
an inner wall comprising:
a) introducing at the proximal end of the vein a valve cutter with a cutter
head having a proximal end, a distal tip, and a plurality of proximally
directed prongs with sharp edges in which the prongs are separated by
slots also having sharp edges, with means for advancing the cutter head
through a vein to render valve leaflets incompetent and fiber optic means
directed distally and positioned proximally to the circular cutting edge;
b) advancing the cutter head up through the vein from the proximal end to
the distal end;
c) reversing the direction of movement of the valve cutter;
d) engaging the leaflets with the cutter head while viewing the cutting of
the venous valve leaflets by the cutting edge as the valve cutter advances
through the vessel and assessing the cut; and
e) rendering successive valves incompetent.
Description
BACKGROUND OF THE INVENTION
This invention is directed generally to rendering venous valve leaflets
incompetent for in-situ arterial bypass in patients requiring arterial
reconstruction for chronic limb-threatening ischemia. More particularly,
this invention is directed to a venous valve cutter having unique improved
cutting surfaces to facilitate the incision of the leaflets and a unique
irrigation system to minimize frictional forces on the endothelium of the
vein when introducing and withdrawing the cutter.
A common form of chronic limb-threatening ischemia, femorotibial,
obstructive disease, typically is treated by using the greater saphenous
vein as a bypass conduit. Traditionally, this vein has been removed from
its anatomic bed and reversed to overcome the obstruction to flow from its
one-way valves. The distal end of the "reversed flow" greater saphenous
vein is then grafted to the femoral artery and its proximal end is grafted
to the outflow artery beyond the obstruction.
There are a number of problems inherent in the use of a reversed flow
saphenous vein as a bypass conduit. The narrow distal end of the vein may
not permit enough arterial in-flow from its new parent vessel, whereas the
wide proximal end of the vein makes an anastomosis to the 2-3 millimeter
distal outflow vessel cumbersome. Also, the body of the vein may twist or
compress and be damaged during the vein removal, reversal and replacement
process and it is difficult to preserve the very sensitive endothelial
layer of the vein during the removal and replacement process. Furthermore,
the process may impair the blood vessel's blood supply (the vasa vasorum).
Bypass procedures in which a vein is used as it lies anatomically within
the body, without removal, reversal and replacement, i.e., "in-situ situ
vein bypasses", generally overcome most problems associated with removing,
reversing and replacing the vein. This is most commonly accomplished in
treating femorotibial disease by moving a valve cutter through the
saphenous vein to incise the venous valve leaflets.
Since Carrel and Guthrie's publication of the techniques required for a
small vessel anastomosis, vascular surgeons have attempted infrainguinal
distal revascularizations. The advantage of the in-situ technique for
saphenous vein bypass are first that the narrow end is anastomosed to the
smaller artery distally with the graft tapering in the appropriate
direction. This improves the hemodynamics at both anastomoses. A second
consideration is that the adventitial blood supply to the vein is
preserved to help protect the endothelial lining of the vein.
Typically, in performing this procedure either the distal end of the vein
is anastomosed to the femoral artery to allow arterial blood to pass into
the vein or a saline solution is pumped through a cannula into the vein to
provide the required pressure to distend the vessel and close the valves.
These procedures are performed to ensure that the valve cutter will meet
and incise the valve leaflets in their closed, extended position. Once all
of the valves are made incompetent, the vein becomes suitable for use as
an arterial bypass conduit.
Unfortunately, it is quite difficult using currently available valve
cutters, to efficiently and consistently incise and render the valves
incompetent without damaging the endothelium of the vein or even piercing
the vein wall. The various currently available valve cutter devices are
difficult to manipulate, often do not center and catch the valve leaves
properly, and can cause significant damage to the vein due to intimal
contact between the surfaces of the cutting head and the vein wall and
tearing at the points of valve attachment to the vessel wall.
U.S. Pat. No. 3,837,345, entitled "Venous Valve Snipper", describes a
device for incising valves in vein grafts to bypass blocked arteries. This
device is not intended to be used in-situ. The instrument has a closed
position and an open position: it is maneuvered past the venous valves in
the direction of blood flow, opened and withdrawn whereby sharp spikes
spear and impale the venous valve leaflets which are then hopefully
incised by closing the device in a scissors-like motion.
U.S. Pat. No. 4,493,321, entitled "Venous Valve Cutter for the Incision of
Valve Leaflets In-situ", describes a valve cutter in the shape of a
reverse arrowhead for preparing a vein in-situ for an arterial bypass. The
valve cutter includes a rounded leader, a cutting blade enclosed in a
protective support, a torsionally rigid rod connecting the leader to the
cutting blade, and a catheter attached to the cutting blade support with
suture material. The valve cutter is used by making proximal and distal
incisions in the vein, passing a rod through the vein, attaching the valve
cutter and pulling it down the vein while introducing fluid through the
attached catheter to close the valves before incising them, and then
returning the valve cutter assembly to the proximal incision. The
orientation of this device must be continuously controlled to prevent the
cutting blade from catching and tearing the orifice wall of a contributing
venous branch and to ensure engagement and incision of both leaflets of
each valve.
U.S. Pat. No. 5,047,041, entitled "Surgical Apparatus for the Excision of
Vein Valves In-situ", describes a valve cutter in which a circular cutting
head affixed to a cable is preceded by a dilating segment also affixed to
the cable. The circular cutting edge has series of rounded guide teeth
which are intended to guide the valve leaflets into cutting grooves which
are supposed to engage and then cut the valve leaflets. Unfortunately, the
rounded unsharpened guide teeth pull, stretch and likely irregularly tear
the valve leaflets before any cutting can begin.
SUMMARY OF THE INVENTION
Accordingly, this invention is directed to an improved venous valve cutter
for in-situ incision of valve leaflets which safely, efficiently, and
consistently renders the venous valves incompetent while minimizing
frictional forces on the endothelium of the vessel and preventing
inadvertent contact between cutting surfaces and the intima of the vein
wall.
An important object of this invention is the provision of a venous valve
cutter for in-situ incision of valve leaflets which does not pull, stretch
or tear the leaflets' attachments to the vessel wall.
Another important object of this invention is the rendering of the venous
valves incompetent for in-situ arterial bypass by cutting blades which
engage and penetrate the valve leaflets immediately on contact with the
cutting head.
A further object of this invention is the provision of a venous valve
cutter with interchangeable cutting heads which enable the surgeon to
appropriately match the head size to a vessel's tapering lumen.
Yet another object of this invention is the provision of an integral venous
valve cutter irrigation system which helps center the device while
irrigating and opening the valves and distending the lumen of the vessel
to prevent contact with the vessel wall as the device is passed up through
the vessel in preparation for the valve cutting procedure.
Still another object of this invention is the provision of a valve cutter
with an irrigation system in which fluid is allowed to pass retrograde
into the cutter head of the device to flush and lubricate its cutting
surfaces.
Yet a further object of the invention is to provide a venous valve cutter
having a cutting head with a cylindrical portion which helps center the
cutter in the vein.
Yet another object of the invention is to provide a venous valve cutter
having a cutting head with a cylindrical portion in which channels are
provided to facilitate fluid passage in tightly fitting vessels.
The improved venous valve cutter of the present invention includes, as a
key feature, a cutter head having a plurality of generally proximally
directed prongs separated by slots, where the prongs have flat forward
cutting edges and the slots also have cutting edges along their entire
length so that the prongs first pierce the valve leaflets whereupon the
cutting surfaces of the slots continue the shearing action as the cutter
moves through the valve. The present invention further includes a unique
irrigation system for valve cutters in which saline or other fluid passes
through the cutter head as the cutter moves through the vessel, first to
minimize trauma as the cutter is passed through the vessel and the valves
and then to minimize trauma and enhance the effectiveness of the shearing
action as the valve leaflets are cut.
BRIEF DESCRIPTION OF THE FIGURES
The features of the present invention which are believed to be novel are
set forth with particularity in the appended claims. The invention,
together with further objects and advantages thereof, may best be
understood by reference to the following description taken in connection
with the accompanying drawings in which:
FIG. 1 is a front plan view of a horizontally disposed, improved venous
valve cutter in accordance with the present invention;
FIG. 2 is an enlarged view of the cutter head and leader of the valve
cutter of FIG. 1;
FIG. 3 is an enlarged end view, in elevation, of the cutter head of FIG. 1,
viewing the cutter head from the pronged end;
FIG. 3A is a modified enlarged end view, in elevation, of the cutter head
of FIG. 1, viewing the cutter head from the pronged end in which channels
are provided to facilitate fluid passage in tightly fitting vessels;
FIG. 4 is an enlarged elevation view of the cutter head of FIG. 1, shown in
section, taken along lines 4--4 of FIG. 3;
FIG. 4A is a schematic representation of a interchangeable valve cutter
head;
FIG. 4B is an elevation view of a blunt-tipped head used to facilitate
placement of the venous valve cutter when interchangeable cutting heads
are to be used;
FIGS. 4C and 4D are elevation views of an alternative unitary
interchangeable valve cutter head and leader design and FIG. 4E is an
elevation view of alternate catheter design which may be fitted to the
valve cutter head and leader of FIGS. 4C and 4D as well as that of FIG. 9
below;
FIG. 5 is an enlarged view of the cutter and leader assembly portion of the
device of FIG. 1, shown in section, taken along lines 5--5 of FIG. 2;
FIG. 5A is an enlarged view of the cutter and leader assembly portion of
the device of FIG. 1, shown in section, taken along lines 5--5 of FIG. 2
in which optional irrigation ports are formed in the cutter head and in
the cutter stem.
FIGS. 6A-6I comprise a diagrammatic representation of the operation of the
valve cutter of FIG. 1;
FIG. 7 is a planar representation of the continuous cutting surface of the
present invention;
FIG. 8 is an enlarged front plan view, shown in section, of a cutter head
in accordance with the present invention, in which provision is made for
back flushing the cutter head as the valve leaflets are excised; and
FIG. 9 is an enlarged partial view of an alternative embodiment of the
improved venous valve cutter of the present invention in which a fiber
optic element is provided for viewing the vessel and the action of the
cutting head in rendering the valves incompetent, and for assessing the
effectiveness of the cut.
DESCRIPTION OF THE PREFERRED EMBODIMENT
An improved venous valve cutter or valvulotome in accordance with the
present invention is generally designated in FIG. 1 by the numeral 10.
Although the valve cutter is discussed below in connection with in-situ
bypass procedures, it is not limited to this and may be applied to any
vascular operation requiring a non-reversed vein graft. Such applications
may, for example, be found during distal infrainguinal bypasses when a
non-anatomic position is required (ex: profunda femoris to anterior tibial
artery), composite vein infrainguinal bypasses, or even an aorta-renal
bypass.
Valve cutter 10 comprises a cutter head 12, a leader 14, a stem 15 between
the cutter head and the leader, a catheter 16, a handle 18 and a
combination hub and injection port 20.
Cutting head 12 may be made of any material which is safe for use in the
body and is capable of taking and holding a knife edge. Stainless steel is
preferred for the fabrication of the cutting head. The valve cutter may,
for example, include 1.5 mm, 2.4 mm, 3.0 mm, and 4.0 mm or other size
diameter cutting heads. The choice of cutter head size is a matter of
judgement although it is recommended that a size smaller than the vein be
employed.
Turning now to FIG. 2, an enlarged view of cutter 12 joined to leader 14 by
stem 15 is shown. The distal end of cutter 12 is in the shape of a cone 22
truncated and bored at its distal tip 24 to provide an irrigation port 26
which communicates with a central lumen 27 (FIGS. 4 and 5). The edge 28 of
irrigation port 26 preferably is rounded in order to minimize the danger
of intimal damage.
Immediately proximal to cone 22, the cutter head surface flows smoothly
into a first cylindrical section 30 which is undercut along its
circumference at 32 to form a second cylindrical section 34 of slightly
lesser outer diameter than the first cylindrical section. This undercut
further minimizes the danger of damage to the vein wall as the cutter
moves past the valves.
A plurality of proximally directed prongs 36 are at the proximal or
"business end" of cylindrical section 34. At least two prongs are
required, although four prongs, 36A, 36B, 36C and 36D are depicted in the
illustrated preferred embodiment, and more can be used. The prongs are
defined by half-oval slots 38 in cylindrical section 34.
The inside edges of prongs 36A-36D, as defined by slots 38, are bevelled
back to a margin 40 and ground to present sharp cutting surfaces 41, as
best seen in FIG. 4. Additionally, the flat leading edges 42 of the prongs
are ground on their inner surfaces at 44 to similarly present sharp
cutting edges. Thus, cutting head 12 is provided with a continuous cutting
surface in multiple planes running along the entire forward edge 46 of the
cutting head, which is shown in FIG. 7 as if the wall of the cutter were
laid out in a plane. As a result, flat leading edges 42 of the prongs
pierce the leaflets whereupon the eight sharp cutting surfaces 41 continue
the shear of the venous valves as the cutter is pulled through to gently
widen the cut in the valve until the apices 43 of the slots are reached
whereupon the entire valve can be cleanly cored out and captured in the
cutter head at 45 (FIG. 5).
The use of leader 14 is preferred but not required in the practice of the
invention. Leader 14 is attached to cutter head 12 through a rigid stem
15, which is centered on the axis of both the cutter and the leader and
forms an open lumen from irrigation port 26 through the distal end 50 of
the leader, as seen in FIG. 5. Also, a rigid spring may be used as stem 15
to provide an additional irrigation site through the spacings between the
coils of the spring. Finally, stem 15 must be of a length sufficient to
permit the valve leaflets to close (clear the leader) before meeting the
leading edges 42 of prongs 38A-38D.
Leader 14 includes a conical surface 70 which flows into a cylindrical
surface 72 and then a trailing conical surface 76. A nipple 78 is provided
at the proximal end of the leader for attachment to catheter 16.
In an alternate embodiment, catheter 16 comprises a tightly wound coil
spring covered with an inextensible sheath. The coil spring is preferably
stainless steel and the sheath is preferably a low surface friction
thromboresistant material such as polyurethane. This sheathed coil
structure is conformable, compliant and flexible yet has longitudinal
rigidity for better centering.
Catheter 16 is attached to plastic handle 18 which may be made of
polyurethane or other suitable materials. The surgeon will grip this
handle as the device is passed through the vein, and may rotate the cutter
head, if desired. However, even without physically rotating the device,
the advancing cutting edges of the prongs produce incisions that advance
about the valve leaflets in a circumvolutory fashion.
The hub/injection port 20 is attached to a source of saline (not shown).
The saline or other fluid flows from the irrigation port distending the
vessel's lumen and aiding in the centering of the device while irrigating
and opening the valves as the valve cutter is passed up through the vessel
in preparation for the valve cutting procedure. This minimizes trauma to
the vessel wall, to preserve a viable, untraumatized and hence
non-thrombogenic endothelium. In an alternative embodiment, depicted in
FIG. 5A, irrigation ports 21 could be formed in cone 22 or in stem 15 to
either enhance the effect of the irrigation from irrigation port 26 or to
replace port 26 which could be capped off.
The present valve cutter adds a particular advantage over other such
devices if the proximal anastomosis is not performed prior to rendering
the valves incompetent since this permits the valve cutter to ensure that
the valves are closed and thus the valves' maximum surface area is exposed
for the cutting blade to engage the valves.
Further, the present valve cutter allows, with a small fiber optic bundle
inserted through the irrigation channel in the valve cutter, direct
observation of the incised valves. In an alternate embodiment, as
illustrated in FIG. 9, a fiber optic bundle 154 is mounted in the leader
14 of the valve cutter to enable the surgeon to view and monitor the
action of the cutting surfaces as they render each successive valve
incompetent.
In yet another embodiment of the invention, underside irrigation is used in
a valve cutter 12A as depicted in FIG. 8. In this embodiment, saline or
other fluid is passed through the catheter 100 and into the rearward
section 102 of the cutting head. The saline accumulates at 102 and is
forced out through ports 104 to flush and lubricate the cutting edges of
the cutting head as they cut into the valve leaflets.
Turning now to FIGS. 6A-6I, valve cutter 10 is introduced through the
proximal end 110 of vein 112 and heparinized saline 114 is irrigated
through port 26 in the cutting head of the valve cutter to dilate and
lubricate vein 112 before the advancing cutting head which is shown
passing up through valve 116, comprising leaflets 116A and 116B, in FIGS.
6B and 6C. The pressure gradient established through irrigation port 26
opens the valve leaflets ahead of the advancing valve cutter (FIG. 6B)
which then passes through the valve as shown in FIG. 6C, well lubricated
by the saline front advancing ahead of it.
When the cutting head of the valve cutter has cleared the valves, its
direction is reversed (FIGS. 6D-6H). The valve cutter is thus positioned
at the most proximal aspect of the vein and gently the hydrostatic
pressure is re-established to close the nearest proximal valve. The
irrigation pressure gradient should be gentle to prevent or minimize
hydrostatic pressure injuries as the valve cutter is gently advanced, with
the vein distended, allowing it to float proximally. The hydrostatic
pressure is maintained so that, with the leaflets closed, leading edges 42
of the cutting head prongs engage the leaflets near the vein wall and
immediately pierce them forming a small incision which is gently widened
by the curved cutting surfaces 41 (FIGS. 6F-6H) until the valve is
rendered incompetent leaving a clean and minimally damaged former valve
site, as seen in FIG. 6I. The irrigation during the process is provided at
a level sufficient to help center the device while minimizing the danger
of hydrostatic pressure injuries to the vein.
The valve cutter 10 is then positioned at the most distal aspect of the
next valve and gently the hydrostatic pressure is re-established to close
that valve which is engaged and gently incised out as described above.
Hydrostatic pressure is maintained and the valve cutter is pulled down,
sequentially engaging and cutting the next distal valve until all the
valves have been rendered incompetent.
If the surgeon wishes to construct a proximal anastomosis prior to using
the valve cutter, thereby allowing the systemic arterial pressure to close
the valves, the irrigation port may be capped off to prevent loss of
blood. However, the proximal anastomosis does not negate the advantage of
irrigation during the initial introduction of the valve cutter at the
distal end of the vein. Also, the surgeon may wish to pass a fiber optic
bundle through the irritation channel to view the cutting of the valves as
the valve cutter proceeds down the vein.
In an alternative embodiment of the invention, as illustrated in FIG. 3A,
channels 110-110D are provided in the cylindrical portion 30 of the cutter
head to permit fluid flow when the cutter head encounters a tightly
fitting portion of a vessel thereby preventing undesirable pressure build
up and ensuring continued lubrication as the cutter passes through the
snugly fitting portion of the vessel.
In yet another alternate embodiment of the invention, a series of
differently sized cutter heads are provided in a kit with a single valve
cutter assembly. This embodiment of the invention is depicted in FIG. 4A
by a representative interchangeable cutter head 120 which has an inner
female threaded portion 122 dimensioned to screw onto a corresponding male
threaded portion 124 at the distal end of stem 126 of the valve cutter
assembly. Thus, differently sized cutter heads with inner threaded female
portions could be substituted for cutter head 120, along with a
blunt-tipped head to facilitate initial placement of the device. The
blunt-tipped head 130, which is illustrated in FIG. 4B, includes a body
132 having a blunt portion 134 and an irrigation port 134, and an
internally threaded portion 135.
An alternative unitary interchangeable cutter head and leader 136 is
illustrated in FIG. 4C. It includes a leader 138 with an inner female
threaded portion 138 dimensioned to screw onto the corresponding male
threaded portion 140 at the end of catheter 142 (FIG. 4D).
Use of the interchangeable valve cutter heads of FIGS. 4A-4C begins by
introducing the valve cutter assembly fitted with the blunt-tipped head
130 through the most proximal end of the vein while heparinized saline is
irrigated through the port to dilate the vein prior to advancing the
device distally. The distal end of the vein is gently closed with a clamp
or between the fingers of an assistant to allow for the dilation of the
vein. With the vein distended, the valvulotome is gently advanced allowing
it to float distally. When the catheter reaches the open sapheno-femoral
junction, (or is passed out through a distal adequate tributary when the
distal anastamosis is performed prior to the valve disruption procedure)
the blunt tip head is removed and replaced with an appropriately sized
valve cutter head. The saphenous vein is again clamped at its open fossa
ovalis. The surgeon must choose a cutting head appropriate for the size of
the patient's greater saphenous vein.
The valve cutter is then positioned at the most distal aspect of the vein.
Fluid is injected through the catheter which distends the lumen and passes
back over the cutting head and closes the valve which is now appropriately
positioned for cutting. The fluid is injected to present a dilated vessel
for the floatation of the device and a functionally closed valve for the
cutting head to engage.
The valve cutter is withdrawn thus engaging and cutting the most distal
valve. Slow and consistent traction is all that is required. The
hydrostatic pressure is maintained and the valve cutter assembly is pulled
down engaging and cutting each sequential valve, until all valves have
been rendered incompetent within the appropriate range relative to the
chosen cutting head. Judgment of the surgeon best determines when the
catheter is again passed back through the unclamped distal sapheno-femoral
junction where the cutting head is replaced with a larger head.
The procedure is repeated and again judgment determines the appropriately
sized cutting head for the vessel's lumen. The appropriately sized valve
cutting head will best cut the valves at a given position in the vessel.
Preferred cutting head sizes include 1.5 mm, 2.4 mm, 3.0 mm and 4.0 mm.
The choice of the particular size is a matter of judgement although it is
recommended that a size smaller than the vein be employed. The ability to
change cutting heads in this catheter allows the surgeon to appropriately
match the heads to the vessel's tapering lumen.
Finally, current devices fitted with fiber optic elements at best permit
the surgeon to view the valve distally and do not permit the cutting edge
to be viewed as it penetrates the valve because the vessel collapses as
the cutter penetrates through the valves. As illustrated in FIG. 9, in the
present device the valve can be visualized proximately so that the cutting
edge can be observed as it penetrates without the vessel collapsing. In
this manner, each and every valve can be observed by the surgeon as the
cutter edge penetrates.
Thus, FIG. 9 illustrates an enlarged partial view of an alternative
embodiment of the improved venous valve cutter of the present invention in
which a fiber optic element is provided for viewing the vessel, the action
of the cutting head in rendering the valves incompetent, and for assessing
the effectiveness of the cut. In this embodiment, the cutting end 150 of
the cutter head is fixed to a leader 152 in which a fiber optic element
154 is mounted. This unique fiber optic mounting permits the surgeon to
observe the cutting edge of the cutter head as it penetrates each valve
using conventional apparatus (not shown).
It should be understood that various changes and modifications to the
preferred embodiments described herein will be apparent to those skilled
in the art. Such changes and modifications can be made without departing
from the spirit and scope of the present invention and without diminishing
its attendant advantages. It is therefore, intended that such changes and
modifications be covered by the following claims.
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